Yogurt contains a variety of bacteria (often called lactic acid bacteria) that are not pathogenic in healthy individuals who have consumed the yogurt. These bacteria include members of the genera Lactobacillus, Bifidobaterium, and Streptococcus. It has been speculated that some of these bacteria may be useful as live oral vaccines. See, e.g., Pouwels et al., J. Biotechnol. 44:183–192, 1996. However, evidence that such live oral vaccines can be efficaciously used in the treatment or prevention of specific diseases or conditions has been lacking.